This invention relates to a three-chambered damper for dampening shock and vibration.
Dampers for dampening shock and vibration between two structural parts limitedly movable against each other are generally formed of elastomers. Elastomer dampers have the advantage that they are inexpensive to manufacture, are immune to corrosion, resistant to wear and tear, and thus are of great durability. However, one disadvantage of such elastomer dampers for a series of applications is the expansion-contraction characteristics inherent to most elastomers which, upon manufacture of the dampening device in a size feasible from the point of view of economy and construction, results in a dampening characteristic which is too soft and a movement which is too great, especially on shock or sudden loading.
Thus an object of the present invention is to provide a damper whose dampening characteristic is similar to that of an elastomer damper but, in contrast to the characteristics of an elastomer damper, can be adjusted or set with simple means, especially for proportional or over-proportional dampening.
In order to obtain this objective, the present invention provides for a three-chambered damper which, in substance, consists of a housing to which one of the two structural members to be dampened is secured, an elastic membrane body being arranged in the housing which is open on one side or is at least provided with a large opening, the elastic membrane body defining in the housing a hydraulically closed system of three chambers which are connected to each other hydraulically through a throttle or dampening passages or openings. The second of the structural members to be dampened relative to the first is secured to the membrane body, wherein this connection grips inside the dampening housing through the open side of the damper housing.
By selecting the size of the three hydraulic chambers as well as their arrangement and providing suitable dimensions and arrangement for the throttle system which connects the three chambers hydraulically among themselves into a cohesive system, it is possible to set up any desired number of dampening characteristics.
The damper housing preferably is made of steel, particularly a steel header that is closed by a sealing cover on one side. The membrane body of an elastomer has in the center thereof a non-deformable connecting block element for connecting thereto the second structural member. Preferably, this connecting block is also made of steel. The securement of such connecting block into the elastomer membrane body is preferably accomplished by vulcanizing the connecting block onto the membrane body.
The membrane body is dimensioned in such a way that its elastic dampening characteristic markedly contributes to the overall dampening characteristics of the three-chambered damper. In other words, the three-chambered damper should preferably not merely be formed as a hydraulic damper, but as a combination damper comprising a hydraulic dampening system and a flexible-elastic or rubber-elastic damper. The flexible-elastic or rubber-elastic dampening characteristic of the membrane body contribute all the more to the overall dampening characteristics as does the membrane walls and the size of the cross-sections of the throttling channels that connect the three hydraulic chambers with each other.
When the membrane body is provided with a connecting block, the throttle channels are formed as bores or passages in the connecting block. This ensures that the throttling channels will not be deformed even at the highest shock load of the damper. Thus they do not change their cross-section and thereby cannot change the dampening characteristic of the dampening device without control. The three chambers that are hydraulically connected to each other are preferably arranged in such a way that one chamber lies over the contact point of the structural member, the second hydraulic chamber lies below such contact point, and the third chamber is arranged symmetrically to the first two chambers in front of the connection of this structural member that grips from the outside into the housing. With such a relatively simple chamber arrangement, optimal three-dimensional dampening can be achieved.
The throttling channel system may, in another embodiment of the three-chambered damper, be replaced by throttling means which establish connection of the fluid between the individual chambers through a central chamber. Preferably, this other type of hydraulical connection between the chambers is obtained by providing a recess in the one frontal part of the connecting block that borders on the chamber which recess represents an extension of the hydraulic chamber. In this case the frontal part of the connecting block is not covered by the elastic membrane body. Rather, this advantageous embodiment of the membrane body is formed with a traversing opening that extends through the middle of the membrane body, the connecting block being vulcanized onto such opening.
The recess formed on the frontal part of the connecting block and into it, which represents the extended part of a hydraulic chamber, is vulcanized onto the membrane body in the manner of an annular reinforcement. In the part that encircles the frontal recess of the connecting block each hydraulic chamber is radially arranged to extend outwardly, and there is provided a traversing channel which aligns with openings in the chambers disposed thereabout. The channel that ends in the extended part of the chamber may, on the one hand, be provided in the vicinity of the bottom surface of the recess wherein the bottom area then constitutes a one-sided channel. In another embodiment these channels may, however, be displaced in relation to the frontal surface edge and have a larger distance to the bottom of the recess than to the surface border. In the latter case, the dampening characteristic of the three-chambered damper is influenced by stronger hydraulic whirling currents in the extended part.
The formation of the channel that ends in the frontal recess of the connecting block and, thereby, of the corresponding opening to the hydraulic chambers is preferably formed on diametrically opposite sides of the recess. When several channels or openings for a chamber are provided, then also a symmetrical or constitutionally provided displacement of these channels may be provided. As long as the action of the forces occurs from predetermined preferential directions and it has been decided to install a three-chambered damper, advantageous dampening characteristics may also be obtained with the displaced arrangement of two channels as contrasted to a diametrical arrangement.
Besides a radically displaced arrangement of the channels which end in the recess of the connecting block, displacement of the channels in the axial direction of the connecting block against each other may be selected to obtain the desired dampening characteristics. With the last mentioned displacement of the channels, which may also be combined with a corresponding axial length of the recess, it will be possible to obtain dampening in the enlarged range of the centrally provided hydraulical chamber without affecting the main area of this hydraulic chamber in any substantial way. The enlarged hydraulic chamber of the three-chambered damper forms what in principle is known as a mushroom form, wherein the capped upper part forms the main chamber and the stem forms the recess that continues in the connecting block. Changed dampening characteristics may, however, be obained by providing the channels that end in the enlarged portion with corresponding diameters and the aligned openings in the chambers. In another variant, the channels to be provided in the walls of a preferably cylindrical recess may also be formed in the direction of the major part of the hydraulic chamber, thus beyond the vertical line of the axis of the connecting block. Thereby the hydraulic medium would firstly be pressed in the direction to the main chamber, whereinanother, almost still volume of the hydraulic medium would be pushed into the complementary chamber.
The three-chambered dampening element of the present invention is preferably used in the automotive industry, namely as a dampening element for motor suspension.
The invention is described in more detail in relation to two illustrated embodiments.
Other features which are considered characteristic of the invention are set forth in the appended claims.
Although the invention is illustrated and described in relationship to specific embodiments, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.